Is responding to food as a reward the same thing as food addiction?

We've had a couple of posts recently about a hypothesis that links the current increase in obesity with an increase in easy access to foods that are designed to trigger reward systems in the human brain. Basically: Maybe we're getting fatter because our brains are seeking out the recurrent reward of food that makes us fat. Scientist Stephan Guyenet explained it all in more detail in a recent guest post.

It's an interesting—and increasingly popular—idea, though not without flaws. To give you some context on how scientists are talking about this, I linked you to a blog post by Scicurious, another scientist who wrote about some of the critiques of food reward and related ideas. In particular, Scicurious questioned some of the implicit connections being made here between body size and health, and eating patterns and body size.

She also talked about another critique, one which came up in a recent article in the journal Nature Reviews Neuroscience. If people are gaining weight because they're addicted to eating unhealthy foods, we ought to see some evidence of that in the way their brains respond to those foods. After all, brains respond to many physically addictive substances in special ways. But we don't see that with junk food. So does that invalidate the hypothesis?

Stephan Guyenet doesn't think it does. In a recent email to me, he explained that he thinks the food reward hypothesis is a bit more nuanced, and can't really be described as "food addiction". At least, not the same way that cigarettes or heroin are addictive.

Addiction is the dependence on a drug, or behavior, despite clear negative consequences. Drug addiction is associated with characteristic changes in the brain, particularly in regions that govern motivation and behavioral reinforcement (reward), which drive out-of-control drug seeking behaviors. Some researchers have proposed that common obesity is a type of “food addiction”, whereby drug addiction-like changes in the brain cause a loss of control over eating behavior. Hisham Ziauddeen and colleagues recently published an opinion piece in Nature Reviews Neuroscience reviewing the evidence related to this idea.

The review concluded that there is currently not enough evidence to treat obesity as a “food addiction”. I agree, and I doubt there ever will be enough evidence. However, this does not challenge the idea that food reward is involved in obesity, an idea I described in a review article in JCEM, on my blog (1, 2), and my recent Boing Boing piece.

The reward system is what motivates us to seek and consume food, and what motivates us to choose certain foods over others. To begin to appreciate its role in obesity, all we need is a common sense example.

Why do some people drink sweetened sodas between meals, rather than plain water? Is it because sodas quench thirst better than water? Is it because people are hungry and need the extra calories? If so, why not just eat a plain potato or a handful of unsalted nuts? The main reason people drink soda is that they enjoy it, plain and simple. They like the sweetness, they like the flavor, they like the feeling of carbonation on the tongue and the mild stimulation the caffeine provides. It’s the same reason people eat a thick slice of double chocolate cake even though they’re stuffed after a large meal. The reward system motivates you to seek the soda and cake, and the hedonic (pleasure) system encourages you to keep consuming it once you’ve begun.

But is this the same as addiction? If I took a person’s cola away, would they get the shakes? Would they break into a convenience store at night to get a cola fix? I’m going to say no.

I agree with Ziauddeen and colleagues that the evidence at this point is not sufficient to say that common obesity represents food addiction, and I appreciate their skeptical perspective on the matter. In obesity, as in leanness, the food reward system appears to be doing exactly what it evolved to do: seek out energy-dense, tasty food, and strongly suggest that you eat it. The problem is that we’re increasingly surrounded by easily accessible, cheap, commercial food that is designed to hit these circuits as hard as possible, with the goal of driving repeat purchase and consumption behaviors. Our brains are not malfunctioning; they’re reacting just as they’re supposed to around foods like this.

45 Responses to “Is responding to food as a reward the same thing as food addiction?”

I read a lot and find myself quite often shopping for used books at flea markets and in junk shops. One of the fascinating things to me is coming across diet book after diet book, each hawking a “new, groundbreaking” way of eating. There were a few popular diet books in the 1960s, but the real explosion in “good eating” titles happened in the early 1980s, along with the US aerobics craze (thank you, Jane Fonda!)

As far as I can tell, basic weight loss happens when a person eats less and exercises more. There may be people who need more complicated regimens. I’m on a diet now and it’s quite difficult to reduce the intake of favorite foods (oh, what I’d give for a handful of Oreos and a glass of milk) – luckily I’m used to daily exercise, so the pounds will begin dropping any minute now

Low carb is the way to go if you need to lose a lot of weight. I lost 30 lbs. over the course of a year with Paleo, 12 of it the first 2 wks. with near 0 carb., and very little exercise. That’s part of what Steven Guynet is saying, its not just about calories in calories out. If it was, then anyone who wants to lose weight would do so pretty easily. Also, completely depriving yourself of your fav foods will make the diet less interesting and difficult to stick to. If you follow Mark Sisson’s advice and use the 80/20 principal a diet is much easier to stick to.

Low carb is indeed a good way to lose a lot of weight, but you can’t ever get away from calories. Low carb works because it actually reduces calorie intake (via lowered food reward stimulation). Implying that low-carb diets work because of some metabolic advantage would be to embrace Taubes’ thoroughly debunked Carbohydrate-Insulin Hypothesis.

Also, I’m pretty worried that “low carb” seems to be equated to “paleo”. In reality the two have nothing to do with each other. For a good counter example of the “low carb cures everything” argument, just look to the Kitavans, who obtain 70% of their calorie intake from carbs and display no signs of obesity nor heart disease.

As far as I can tell, basic weight loss happens when a person eats less and exercises more.

The exercise versus quantity argument is moot even if you’re filling your face with an eye dropper filled with indigestible crap.

The whole obesity epidemic started in the ninety-seventies after Earl Butz waged the American version of Stalin’s agrarian revolution. There was no mention of an obesity epidemic before then because obesity was a rare disease. However, Butz’s approach of subsidies and financial incentives to farmers to let some fields lie fallow and rotate crops grown actually worked.*

The problems began when Richard M. Nixon started shipping huge quantities of US wheat production to Russia, in response to at the time ongoing Ukrainian crop failures, and in order to replace wheat, Butz embarked the US in a giant agrarian program to supplant and replace wheat with another crop: corn.

Unfortunately corn, which had always been considered pig slop in Europe (which is why Russians would go to war before eating it,) is not as digestible and easily metabolized as wheat (with its problem of gluten) or as easily digested as rice. (End result: marbling of fat and muscle tissue. [Obesity is marbling of more fat and less muscle tissue.])

The subsidies for corn have resulted in corn being used in everything from our clothes to our gas tanks and corn and its derivatives are used in every product or the production of every product in every aisle of the grocery store.

If we compound the problems of the digestibility/metabolization of corn itself with the need for/use of preservatives for corn based products we arrive at the second half of the problem: our indiscriminate use of food preservatives.

Ask yourself the following question: “If something as undiscriminating as bacteria won’t eat stuff that’s left for weeks on a grocery store shelf, is it really smart for me to put it in my mouth and swallow it?”

While I laud the coming of refrigeration, I curse the coming of chemical preservatives synthesized from oil. (You know, all the additives with unpronounceable names at the end of the nutrition label. They maybe be present in near trace amounts but they are not breaking down with digestion, [that’s why BisPhenol-A, which has estrogen like properties, is present everywhere in the fatty tissue of every living person on earth,] or worse, it is breaking down into constituents with toxic effects.)

*) The sad part of this story is that our reliance on chemical fertilizers has led to the U.S. now having the same kind of monoculture, corn grown farther than the eyes can see, that led partly to the Ukrainian wheat crop failure [1930–1937] and recurred in the sixties (and the sensitivity to a blight that led to the Irish potato famine of the nineteenth century [1845-1852].)

The problem is that we’re increasingly surrounded by easily accessible, cheap, commercial food that is designed to hit these circuits as hard as possible, with the goal of driving repeat purchase and consumption behaviors. Our brains are not malfunctioning; they’re reacting just as they’re supposed to around foods like this.

The Ph.Ds who understand these principles best are often the ones hired by big corporations to exploit it as much as possible. It’s hard to fight for good when the forces of evil pay so well.

And to take it further, those same Ph.Ds who were hired by those corporations are the same ones that “retire” from those companies and are posted to the FDA or the USDA, mostly the latter. Members of the Supreme Court own stock in these companies.

Seed blowing in the wind off a Monsanto truck on a highway lands in a farmer’s field. Three months later, Monsanto checks that farmer’s crop to see that his wheat has the Monsanto gene marker in 10% of his plants. He is accused of theft and absolutely ruined. And thus, the corporation advances.

The theory that makes the most sense to me was demonstrated in a recent BBC Horizon documentary on fat. They did blood tests on “normal” weight people and obese people before and after eating and showed that obese people did not get the spike in satiation hormone that normal weight people do. So basically obese people are never really “done” eating.

It sounds innocuous and ignorable enough, but it’s like the water drip torture, impossible to ignore indefinitely. A cruel complication is added when those with normal hormone response can’t comprehend why those without it can’t just simply eat less.

The only known way to restore the satiation spike currently is through stomach reduction surgery, which does not work in the way everyone assumes (by simple volume and absorption reduction). In fact, they don’t yet know why it restores the hormone spike, or why the spike disappears to begin with.

So rather than quibble over the term “addiction”, maybe it would be a better use of our time to investigate why sugars, fats, and salts are being deliberately engineered into our foods in order to make them hyper-palatable and therefore conditioning people to prefer processed foods and drinks over more natural alternatives?

I can understand the desire for scientific purity but most reasonable people understand that “food addiction” is simply a euphemism for not being able to stop eating junk that we know are bad for us but we do it anyway.

Food addiction might not be a physiological addiction but I’m pretty sure it meets all the criteria for a psychological one.

Why? Because they sell, and at present anyone in the US who questions the right of corporations to market such things and individuals to buy them, or even just to take away the subsidies that make them so cheap, is immediately branded a socialist, or anti-american, or some such.

I have a few guilty pleasures, sure. But I mostly eat to fuel my body. Taste is nice, but secondary. If anybody whosoever bothers to cook me a meal, I will eat every bite, regardless. Every once in a while, I find myself really looking forward to a meal with almost orgiastic countenance. Maybe as much as once a month, so not often. But I have been told by professionals that weekend binge drinking is worse than staying constantly drunk, so what do I know? I tend to consume 2,800 calories a day, but am not as active as I should be, although I regularly lift weights. At 42, I am 6′ 3″ and 175 pounds. You tell me. Am I a food addict? Well, seeing as how a total lack of food is a serious bummer, yeah – I guess I am. I’d even go so far as to say that every human born was addicted to food and the cycle will continue.

People eat for many reasons that go beyond the “food is fuel” approach. I would argue that emotional binge eating is just as serious and dangerous as binge drinking – with perhaps longer term consequences as well.

I think the issue here is trying to apply a scientific hypothesis that equates food = drugs with the logical argument that too much of either represents an “addiction” that can be measured according to the accepted standards of what constitutes a physical dependency.

The human body needs food to survive – so one one level, it’s technically impossible to be truly “addicted” to something the body needs for survival….much like it’s probably impossible to be “addicted” to water. But water, ingested in an uncontrolled manner and in sufficient quantities can be just as deadly.

We may never be able to prove true “food addiction” – but the evidence is clear that some people eat way more than they should of stuff that is very unhealthy despite repeated warnings that this behavior is going to eventually kill them. If that’s not an addiction, then I don’t know what is.

I would seriously eat a fixed portion of Unimix or similar every day to survive if it was available commercially.

I find the problem I have with eating is that I am a lazy cook in a shared home, and I find myself putting off cooking and becoming used to the pleasurableness of any given menu item, so a plesantly bland stomach filler would prevent me from reaching for the first thing at hand (usually bread or a can of soup).

A part of me wonders if some portion isn’t a result of just bad food. We call junk food a super stimulus- and for a particular subset of tastes it truly is. But personally, I find that I feel less satiated after eating less flavorful food (compare a fine cheese to commodity cheddar, or a curry to something steamed). This results in me snacking soon after. Most junk food, for me, falls into this category- I eat it, I enjoy the fat and sweetness, but soon afterwards I’m still hungry.

Protein is the best macronutrient for hitting the satiety buttons. Fats cause food to stay in the stomach longer (which is good if you’re eating healthy fats). Adding protein will make you feel sated quicker and longer.

No offense but, this post is misguided. At least if you take the word of the world’s number one expert on addiction – National Institute on Drug Abuse Director Nora Volkow – who says, “The data is so overwhelming the field has to accept it. We are finding tremendous overlap between drugs in the brain and food in the brain.” http://www.foodaddictionsummit.org/docs/5Wang.pdf

If you’ll follow the link to the Nature Reviews Neuroscience journal article (or the post by Scicurious that summarizes that article) you will find that the evidence is really not as clear-cut as you are making it sound here.

“Addiction is the dependence on a drug, or behavior, despite clear negative consequences.”

I think most people would consider obesity to be a clear negative consequence.

“If I took a person’s cola away, would they get the shakes? Would they break into a convenience store at night to get a cola fix? I’m going to say no.”

This argument is silly. When an alcoholic gets “the shakes,” it is the result of that drug’s unique pharmacology. Relatively few addictive drugs cause this symptom when withdrawn. Powerful craving is the hallmark of addiction.

Furthermore, you wouldn’t say that a person isn’t an alcoholic just because they haven’t broken into a convenience store. Yet sugar soda is even less expensive and more easily obtainable than alcohol.

” in the way their brains respond to those foods” – you have to re-think that… you are NOT a lab rat, you are not watching yourself in a bad dream of terrible chemicals being poured down your throat, you are not subject to what the scientific media will tell you is the ‘problem’, there’s no master puppeteer stuffing junkfood into your mouth.
if you as a fat person are capable of comprehending that, then you have to accept the fact that since it’s “your brain”, “you” are ultimately responsible for your brain’s decisions (NO MATTER WHOSE FAULT IT IS). If not, then you might as well commit yourself to an asylum. There is such a strong tendency to point the finger now that science is getting funded to tell us why we’re fat.
“(oh, what I’d give for a handful of Oreos and a glass of milk)” – a handful?! seriously?! “your brain” cannot process that two cookies is enough for this afternoon?! or that you don’t even need one today? (yes, it can – the real problem is YOUR discipline). “your brain” should not run your credit out of range, and “your brain” should not run your weight up by eating handfuls of sugar. in the financial reality, your credit report/mortgage/etc. is your discipliner, in the food reality, you are. simple. the bank could not give a flying f@#& how many cookies you eat. too bad that diet and exercise is a tough go, so is bankruptcy. now go for a walk, and TELL YOUR BRAIN what satiation is. “your brain” will eventually get it. then ‘you’ and ‘your brian’ will no longer be separate realities, like “You” and “your Body” now are.

“if you as a fat person are capable of comprehending that, then you have to accept the fact that since it’s “your brain”, “you” are ultimately responsible for your brain’s decisions (NO MATTER WHOSE FAULT IT IS). If not, then you might as well commit yourself to an asylum. There is such a strong tendency to point the finger now that science is getting funded to tell us why we’re fat.”

Hmm… yes, well… that really doesn’t help much, does it? Sure, nobody is, for instance, forcing anybody to smoke. I hear it’s not that easy for most to stop. Same for drugs… alcohol… and yes, eating too much food.

When on a normal diet I have these “little voices” in my head to eat more. More. MORE. When I’m on a low carb diet they stop… mostly… at least to a level I can mostly ignore them. Sure, they are not really “little voices”, nobody is forcing me… but what they are is a horrible urge and need that won’t relent until it is satisfied. I would guess a bit like a tic. Sure, it is me who decides to satisfy that need… but… it would be easier without that darn thing in my head.

True, the urge is strong, but it is still mind over matter. I went near 0 carb to lose weight and when I started adding carbs back I figured out that I am gluten sensitive. Now when I eat wheat, especially whole wheat, I get heart burn and my ADD goes crazy. But I overcame it by realizing that I am in charge, not the urges. The same goes for having overcome alcohol and nicotine. Mind over matter.

Good for you, and I really mean it! Me… well… I do notice that portion control helps, constant smaller meals for some reason means less of a voice in my head. But… I have to actually have access to only small portions. Free access to food… not a good idea. Low carb works even better, but… I haven’t kicked myself enough into gear to start it again (it really is a pain in the butt… I did strict low carbing for over a year, lost a lot of weight… but… always fixing your own food started to get really old).

And yes, I’m not gluten sensitive (small intestine biopsy says no), but there is definitely something in wheat that doesn’t agree with me. I’ve always had it, but it has gotten worse with age and I really need to limit it or I get some killer heart burn (and other fun symptoms).

If I’m understanding Guyenet correctly, the subjective enjoyment of foods is a side-effect of the food reward system. That is, by the time you become consciously aware of the enjoyable aspects of eating a certain kind of food, the reward system has already been activated by the food.

Put another way, the subjective enjoyment is caused by the reward system.

Yes, and that subjective enjoyment is to a large extent determined by your genetics – specifically how many and what kind of dopamine receptors you have in your brain, according to Nora Volkow, Director of the National Institute on Drug Abuse.

I believe it is a combination of Pavlov’s dog and evolution. The physiological reactions started with the need to fatten up for the winter. Now we are conditioned to enjoy them and they are widely available. The problem lies with the fact that our bodies have not evolved to use junk food as our primary source of energy and nutrition (mainly because it is nearly void of nutrition.)

But the body’s “reward system” (primarily the dopamine pathway called the medial forebrain bundle) becomes gradually desensitized to artificial overstimulation (e.g. with cocaine), so it requires ever-higher doses to feel good.

Meanwhile, when you eat a lot of “junk” foods, your body’s “thermostat” – the hypothalamus – can lose sensitivity to appetite-regulating hormones like leptin, which “reports” via your bloodstream that you’ve had enough to eat.

Overstimulation (as with nicotine, alcohol and methamphetamine) can also very quickly destroy a very slender bundle of nerves called the fasciculus retroflexus, which carries impulse and behavioral control signals from “executive control centers” in your cortex to your primitive emotional, instinctual behavior centers (your limbic system and midbrain/hindbrain), and regions that govern craving signals (such as your habenula and hypothalamus).

These parallel changes to your brain and body are the basis of addiction – and why it’s so incredibly hard to stop once an addiction has you in its grip. The neural pathways that give you control over your destructive behaviors have been destroyed. Read about it in The Path Book II.

I have been following Dr Guyenet’s blog off and on for a while now but still remain more persuaded by the argument that it’s not so much about how MUCH you eat or exercise but WHAT you eat; that some foods are more quickly partitioned into fat cells, namely processed sugars and grain flours.

I don’t think the food reward idea explains the situation in poverty-stricken countries where obesity is prevalent despite the fact that there is little food available, eg, children show signs of malnutrition while their mothers are obese.

That said, whether it is correct or not, the food reward idea leads you to largely the same diet as a low carb/paleo diet, that is, avoid processed foods, eat whole foods and good fats, don’t be afraid of meat.

Dr. Guyenet’s soda pop example is a good one. I also like the potato chip example. Can anyone explain why it’s so much harder to eat just one potato chip than just one chunk of boiled potato without using a concept akin to food/brain reward?